feat: add solutions to lc problem: No.0611.Valid Triangle Number

Author: maolonglong

solution/0600-0699/0611.Valid Triangle Number/README.md

@@ -14,7 +14,7 @@
 <strong>输入:</strong> [2,2,3,4]
 <strong>输出:</strong> 3
 <strong>解释:</strong>
-有效的组合是: 
+有效的组合是:
 2,3,4 (使用第一个 2)
 2,3,4 (使用第二个 2)
 2,2,3
@@ -32,22 +32,82 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
+双指针加二分，先枚举两条边，然后利用二分查找定位第三条边
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def triangleNumber(self, nums: List[int]) -> int:
+        n = len(nums)
+        nums.sort()
+        ans = 0
+        for i in range(0, n - 2):
+            for j in range(i + 1, n - 1):
+                left, right = j + 1, n
+                while left < right:
+                    mid = left + (right - left) // 2
+                    if nums[mid] < nums[i] + nums[j]:
+                        left = mid + 1
+                    else:
+                        right = mid
+                ans += left - j - 1
+        return ans
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
+class Solution {
+    public int triangleNumber(int[] nums) {
+        Arrays.sort(nums);
+        int n = nums.length;
+        int res = 0;
+        for (int i = n - 1; i >= 2; --i) {
+            int l = 0, r = i - 1;
+            while (l < r) {
+                if (nums[l] + nums[r] > nums[i]) {
+                    res += r - l;
+                    --r;
+                } else {
+                    ++l;
+                }
+            }
+        }
+        return res;
+    }
+}
+```
 
+### **Go**
+
+```go
+func triangleNumber(nums []int) int {
+	n := len(nums)
+	sort.Ints(nums)
+	ans := 0
+	for i := 0; i < n-2; i++ {
+		for j := i + 1; j < n-1; j++ {
+			left, right := j+1, n
+			for left < right {
+				mid := int(uint(left+right) >> 1)
+				if nums[mid] < nums[i]+nums[j] {
+					left = mid + 1
+				} else {
+					right = mid
+				}
+			}
+			ans += left - j - 1
+		}
+	}
+	return ans
+}
 ```
 
 ### **...**

solution/0600-0699/0611.Valid Triangle Number/README_EN.md

@@ -18,7 +18,7 @@ Given an array consists of non-negative integers,  your task is to count the num
 
 <b>Explanation:</b>
 
-Valid combinations are: 
+Valid combinations are:
 
 2,3,4 (using the first 2)
 
@@ -48,18 +48,78 @@ Valid combinations are:
 
 ## Solutions
 
+First enumerate two edges, and then use binary search to locate the third edge.
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 ```python
-
+class Solution:
+    def triangleNumber(self, nums: List[int]) -> int:
+        n = len(nums)
+        nums.sort()
+        ans = 0
+        for i in range(0, n - 2):
+            for j in range(i + 1, n - 1):
+                left, right = j + 1, n
+                while left < right:
+                    mid = left + (right - left) // 2
+                    if nums[mid] < nums[i] + nums[j]:
+                        left = mid + 1
+                    else:
+                        right = mid
+                ans += left - j - 1
+        return ans
 ```
 
 ### **Java**
 
 ```java
+class Solution {
+    public int triangleNumber(int[] nums) {
+        Arrays.sort(nums);
+        int n = nums.length;
+        int res = 0;
+        for (int i = n - 1; i >= 2; --i) {
+            int l = 0, r = i - 1;
+            while (l < r) {
+                if (nums[l] + nums[r] > nums[i]) {
+                    res += r - l;
+                    --r;
+                } else {
+                    ++l;
+                }
+            }
+        }
+        return res;
+    }
+}
+```
 
+### **Go**
+
+```go
+func triangleNumber(nums []int) int {
+	n := len(nums)
+	sort.Ints(nums)
+	ans := 0
+	for i := 0; i < n-2; i++ {
+		for j := i + 1; j < n-1; j++ {
+			left, right := j+1, n
+			for left < right {
+				mid := int(uint(left+right) >> 1)
+				if nums[mid] < nums[i]+nums[j] {
+					left = mid + 1
+				} else {
+					right = mid
+				}
+			}
+			ans += left - j - 1
+		}
+	}
+	return ans
+}
 ```
 
 ### **...**

solution/0600-0699/0611.Valid Triangle Number/Solution.go

@@ -0,0 +1,20 @@
+func triangleNumber(nums []int) int {
+	n := len(nums)
+	sort.Ints(nums)
+	ans := 0
+	for i := 0; i < n-2; i++ {
+		for j := i + 1; j < n-1; j++ {
+			left, right := j+1, n
+			for left < right {
+				mid := int(uint(left+right) >> 1)
+				if nums[mid] < nums[i]+nums[j] {
+					left = mid + 1
+				} else {
+					right = mid
+				}
+			}
+			ans += left - j - 1
+		}
+	}
+	return ans
+}

solution/0600-0699/0611.Valid Triangle Number/Solution.py

@@ -0,0 +1,16 @@
+class Solution:
+    def triangleNumber(self, nums: List[int]) -> int:
+        n = len(nums)
+        nums.sort()
+        ans = 0
+        for i in range(0, n - 2):
+            for j in range(i + 1, n - 1):
+                left, right = j + 1, n
+                while left < right:
+                    mid = left + (right - left) // 2
+                    if nums[mid] < nums[i] + nums[j]:
+                        left = mid + 1
+                    else:
+                        right = mid
+                ans += left - j - 1
+        return ans